The introduction of nanoscale reinforcing elements into the quasicrystalline Al–Cu–Fe matrix is a promising approach to improving the mechanical properties of composite materials. Tin, due to its plasticity and relatively low melting point, can effectively modify the structure and deformation behavior of the quasicrystalline matrix. This work is devoted to the study of the mechanical structural transformation occurring in the quasicrystalline Al–Cu–Fe nanocomposite reinforced with tin under the influence of mechanical loads.
Experimental methods included preparation of nanocomposites by mechanical alloying followed by consolidation by spark plasma sintering. Microstructural studies were conducted using high-resolution transmission electron microscopy, which allows visualization of the composite structure at the nanoscale. Mechanical tests included nanoindentation and compression at room temperature.
The discovery of quasicrystals (QCs) in Al–Mn alloy by Shechtman and colleagues in 1984 marked the emergence of a new class of aperiodic crystals and revolutionized traditional concepts of crystallography. QCs are complex intermetallic compounds characterized by aperiodicity, high strength, excellent wear resistance, low friction coefficient, low electrical and thermal conductivity, and good corrosion resistance.
Following the first discovery of quasi-crystallinity in an Al–Mn alloy, many similar phases and alloys have been found in aluminum-based systems. Among the widely used aluminum-based ternary quasi-crystalline alloys, the Al–Cu–Fe system is the most studied due to its non-toxicity, cost-effectiveness, and availability of its constituent elements.
The aperiodic crystal structure combined with outstanding functional properties makes them promising structural materials for use in coatings, as reinforcing elements in aluminum-based composites, and as substrates for catalytic processes. To obtain a stable IQC phase in ternary Al–Cu–Fe systems, it is necessary to maintain the composition in the range of 58–70 at.% Al, 20–28 at.% Cu, and 10–14 at.% Fe.
The results show that the introduction of tin leads to the formation of a heterogeneous structure with a uniform distribution of nanosized tin particles in the quasi-crystalline matrix. Nanoindentation demonstrates an increase in microhardness and elastic modulus compared to pure Al–Cu–Fe quasicrystal. The deformation behavior of the composite is characterized by plastic flow caused by the deformation of tin particles and the activation of slip mechanisms in the quasi-crystalline matrix. Analysis of the structure after deformation reveals the formation of dislocations and amorphous regions near the interfaces between the quasi-crystalline matrix and tin particles.
Tin-reinforced Al–Cu–Fe nanocomposites exhibit improved mechanical properties due to structural changes occurring under mechanical loads. The plasticity of tin ensures effective stress distribution and promotes the activation of deformation mechanisms in the quasi-crystalline matrix.
Author: Yagnesh Shadangi, Vikas Shivam, Somarouthu Varalakshmi, Joysurya Bas, Kausik Chattopadhyay, Bhaskar Majumdar, NK Mukhopadhyay
Institute: Department of Metallurgy, Indian Institute of Technology (BHU), Varanasi, 221005, Uttar Pradesh, India, Department of Materials Science, Defence Institute of Advanced Technology, Pune, 411025, Maharashtra, India